(1) This internal pressure stiffens the trunk into a more rigid structure. Thus,
one uses Valsalva's maneuver to provide support for a strenuous effort with the upper
(2) When Valsalva's maneuver is followed by a sudden opening of the rima
glottidis, the result is a cough. This is used to clear the air passageways.
(3) An individual whose trunk wall muscles are paralyzed cannot do these
7-29. PRODUCTION OF HUMAN SPEECH
Human speech is a combination of a number of processes. Essentially, a
column of air flows out through the oral cavity, where it is chopped into bits of speech
known as phonemes.
a. Speech sounds produced when the oral cavity is not blocked are called
vowels. Sounds resulting from the closing or chopping action of the oral cavity are
known as consonants.
b. The column of air vibrates at different frequencies (pitch). These vibration
frequencies are gained by the air as it passes through the larynx. The pitch is varied by
a change in the tension of the vocal cords. The higher the tension, the higher will be the
Section VIII. THE "RESPIRATORY TREE" AND PULMONARY ALVEOLI
The infralaryngeal structures (Figure 7-4) include the "respiratory tree" and the
lungs. The respiratory tree is so named because it has the appearance of an inverted
tree, with its trunk and branches. It is essentially a tubular structure connecting the
larynx to the alveoli of the lungs. This tubular structure is lined with a ciliated
epithelium. (Remember, cilia are hair-like projections from cells.) The tubes are kept
open (patent) by a series of ring-like structures of cartilage.
The "trunk" of the tree is the trachea. The trachea extends from the inferior
margin of the larynx, down through the neck, and into the center of the thorax.